1. Field
Exemplary embodiments of the present invention relate to a transistor, and more particularly, to a transistor having a dual work function buried gate electrode and a method for fabricating the same.
2. Description of the Related Art
A metal gate electrode may be applied as the gate electrode of a transistor. Gate resistance may be decreased by a metal gate electrode that has a low resistance. Additionally, since the metal gate electrode may have a high work function, the channel dose may be decreased resulting in a reduction of leakage current and improved transistor performance.
However, a concern is likely to be caused due to the high work function, since gate-induced drain leakage (GIDL) increases where the metal gate electrode and junction regions overlap, in the source/drain regions. Particularly, in a buried gate type transistor, since the overlap area between a buried metal gate electrode and source/drain regions is large, gate-induced drain leakage (GIDL) may be an issue.
To reduce gate-induced drain leakage (GIDL), the height of the buried metal gate electrode may be lowered and the overlap area between the buried metal gate electrode and the source/drain regions may be minimized.
Nevertheless, if the height of the buried metal gate electrode is lowered, there is a concern that gate resistance increases and the current drivability of the transistor is degraded.
Hence, an improved trade-off characteristic between gate-induced drain leakage (GIDL) and current drivability is in demand.